Well, they released Artifact in 2018 (to poor reception), DOTA Underlords in 2019 (and stopped updating it after a while), and half life alyx in 2020.
https://store.steampowered.com/search/?sort_by=Released_DESC...
They also likely have another half-life game in the works, as mentions of half-life-esque things have popped up around their codebase (as published through updates of their existing source 2 games):